Many examples of underwater devices exist which have exhaust systems that expel the exhaust air or mixed gases into the surrounding water during their normal functions. One example of these related art systems is the Second Stage Regulator used for self-contained underwater breathing apparatus (SCUBA) divers.
Some SCUBA diving setups include a tank of compressed air or mixed gases that is worn by the diver, a first stage regulator attached to the tank that reduces the compressed air pressure form 3000 psi to around 150 psi, a hose that connects the first and second stage regulators, and a second stage regulator being held in the diver's mouth that reduces the pressure from 150 psi to ambient pressure and that supplies the air to the diver upon demand.
The SCUBA second stage regulator includes the following components: a regulator housing, a flexible diaphragm that collapses inwardly during the inhalation cycle against a small lever that activates an inhalation valve for supplying the diver with air, an exhaust valve which is used as a one way valve to allow the exhaust air or gases to escape the regulator housing during the exhalation cycle, a bubble deflector to guide the exhaust bubbles out of the way of the diver's vision, and a mouth piece to seal out the surrounding water and to hold the regulator assembly in the diver's mouth.
The exhaust air or gases exit the SCUBA second stage regulator travels through an opening in the wall of the regulator housing. An exhaust valve is mounted on the outside, covering this opening, and is used as a one-way valve to control the direction of flow of the exhaust gases. The circular opening has one or more cross bars that go from one side of the opening to the other side and are to be used as a mounting area for the exhaust valve and to help prevent the exhaust valve from collapsing inwardly when there is a negative pressure experienced.
Exhaust valves comprise a molded flexible rubber or silicone and are usually made in round disk or mushroom-type shape. They are designed to flex or peel away under pressure to open and close. The purpose of the exhaust valve is to control the direction of flow of the exhaust gases and to keep the surrounding water out of the regulator once the flow of gases has stopped.
Many of the SCUBA second stage regulators exhaust directly into the surrounding water without any backflow prevention features. This circumstance involves the water being in direct contact with the entire outside surface of the exhaust valve. Most of the second stage regulators also have the exhaust valve(s) mounted at an angle an in the low point within the regulator housing. This configuration helps to collect any water that has entered the regulator at or near the bottom of the system so that the water can be cleared or purged.
A few reasons exist for exhaust valves having water seepage, or leakage back, into the regulator. One reason is that a condition of “under-pressure” occurs during the inhalation cycle. This under-pressure causes an inward flexing of the exhaust valve, thereby distorting the valve against the edge of a circular opening and cross bars, and thereby the valve to leak. Another reason is that a water flow catches the outside sealing edge of the exhaust valve, thereby flexing the valve into an open position, and thereby causing the valve to leak.
Several reasons exist for water flowing outside the exhaust valve. One reason is that, when the diver enters the water somewhat rapidly, i.e., by either jumping or sliding, the water very quickly floods the open areas of a bubble deflector. Further, the water rushes into the valve by flowing around the outside surfaces of the exhaust valve. The water catches the edge of the valve, thereby flexing the valve, and thereby causing the valve to leak.
Another reason for water leaking around the exhaust valve is a laminar flow of water that is created by the exhaust bubbles. Once the exhaust gases travel through the circular opening and past the exhaust valve, the gases become, or create, bubbles. These bubbles are naturally buoyant and travel upward toward the surface of the water. As the bubbles are traveling upward, they affect the surrounding water in which they are in contact, thereby drawing the water upward as well, and thereby creating a laminar flow of water which flows on, and past, the exterior surfaces of the exhaust valve.
The related art exhaust valves have been designed to provide low exhaust resistance during heavy breathing rates. This circumstance has resulted in the related art valves becoming somewhat larger (1″-1.5″ in diameter) or the systems having multiple or several valves. When the diver is breathing at a lower or moderate rate, only the upper portion of the exhaust valve is used while the lower portion remains in the closed position. The laminar flow of water created by the bubbles exiting the top portion of the valve catches on the lower sealing edge of the exhaust valve, thereby causing the valve to leak. Seepage or leakage of water via the exhaust valve is a nuisance, at best. However, a leakage condition can be a dangerous situation if diving is performed in contaminated or polluted water.
Another common feature of most of the SCUBA second stage regulators is a bubble deflector. The bubble deflector is made of a molded rubber or plastic and is mounted around, or adjacent, the exhaust valve(s). The purpose of the bubble deflector is to capture the exhaust bubbles and divert them away from the front of the diver's face to provide a good line of vision.
The related art bubble deflectors include bubble exit openings that are large enough to allow water to enter the lower half or lower portion of the bubble exit opening, while the bubbles escape from the top half or top portion of the bubble exit opening. The water entering at the lower half or lower portion of the bubble exit opening is part of the laminar flow of water that the bubbles create.
FIG. 1 shows a gas exhaust system for a SCUBA apparatus, in accordance with the related art. A related art exhaust valve covers the opening where gas exits the system. The exhaust valve is circular; and the path that the exhaust takes is shown by the directional arrow B. Water that is external to the system travels in a path following the directional arrow A. When gas exhausts from the system, it will do so at the top (or where pressure is the lowest), as indicated by the minus sign. The water will travel upward with the bubbles to create a laminar flow of water across the exterior of the exhaust valve. This laminar flow of water catches the lower sealing edge of the related art exhaust valve, thereby causing the valve to leak as experienced in the related art. Furthermore, water enters the system through the bottom of the related art exhaust valve due to the flow created. As such, a long-felt need exists for an underwater exhaust system in which leakage is at least minimized and preferably eliminated altogether.